ABSTRACT Allergic disease is the fifth leading chronic disease in the United States. A major contributing factor to allergic inflammation including asthma is Prostaglandin D2 (PGD2) produced by mast cells, the cell type responsible for IgE-mediated immediate hypersensitivity reactions. Therefore, targeting the arachidonic acid pathway in mast cells to inhibit PGD2 biosynthesis is one strategy to significantly limit allergic inflammation. Recently, we discovered that Resveratrol, a natural plant-derived polyphenol, selectively inhibited IgE-dependent PGD2 production from human skin mast cells. We further showed that Resveratrol inhibited Fc?RI-induced expression of cyclooxygenase 2 (COX-2), a key enzyme in the arachidonic acid pathway that is directly involved in PGD2 biosynthesis. The central question of this study is: how does Resveratrol inhibit Fc?RI-induced COX-2 expression and PGD2 production in mast cells? Interestingly, miR-155 has been implicated as a positive regulator of COX- 2 expression in different cancers, macrophages, airway smooth muscle, and in the severity of allergic asthma in mice. Indeed, our miRNA array analysis and qRT-PCR validation studies revealed a positive correlation between miR-155 and COX-2 expression in human primary mast cells following Fc?RI crosslinking. Moreover, we found that Resveratrol significantly inhibited Fc?RI-induced expression of miR-155 expression as well as COX-2. Given that miRs negatively regulate target genes, these data suggest that miR-155 targets a repressor of COX-2. Our in silico pathway analysis has identified several negative regulators of COX-2 such as ATF3, SOCS-1, SHIP-1, and PPARG, as potential targets of miR-155 in human and murine mast cells. Thus, we hypothesize that Resveratrol inhibits allergic inflammation by regulating the expression of miR-155 in mast cells leading to increased induction of the repressors and consequently diminishing COX-2 expression and PGD2 biosynthesis. Our study will (1) Characterize the effect of Resveratrol on the Fc?RI-induced miRNA expression profile in in situ-matured mast cells from human and mouse, (2) Identify the COX-2 repressor targeted by miR-155, and define the mechanism by which Resveratrol inhibits Fc?RI-induced COX-2 expression and PGD2 biosynthesis in mast cells, and (3) Characterize the effects of dietary Resveratrol on airway remodeling and hyper- responsiveness in a mast cell dependent model of allergic asthma, and identify associated miRNAs. To define the role of miR-155-5p in allergic asthma and the efficacy of Resveratrol in inhibiting disease development, we will also use miR-155-5p transgenic (Tg) and knockout (KO) mice in our model. Overall, this study will shed new light on the role of miR-155 in the ability of Resveratrol to selectively inhibit Fc?RI-induced COX-2 and PGD2 production in mast cells, thereby, attenuating allergic inflammation.